<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
	<style>
		.c{
			width:0px;
			border-style:solid;
			border-width:100px;
			border-top-width:0px;
			border-color:green transparent red transparent;
		
		}
		.d{
			width:0px;
			border-style:solid;
			border-width:100px;
			border-top-width:0px;
			border-color:yellow red green transparent;
		}
		.b{
			width:0px;
			border-style:solid;
			border-width:100px;
			border-top-width:0px;
			border-color:red transparent transparent green;
		}
	</style>
</head>
<body>
	<div class="c"></div>
	<div class="d"></div>
	<div class="b"></div>
</body>
</html>